/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.android.photos.data;

import android.content.ContentProvider;
import android.content.ContentResolver;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.DatabaseUtils;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteStatement;
import android.net.Uri;
import android.os.CancellationSignal;
import android.provider.BaseColumns;

import java.util.ArrayList;
import java.util.List;

/**
 * A provider that gives access to photo and video information for media stored
 * on the server. Only media that is or will be put on the server will be
 * accessed by this provider. Use Photos.CONTENT_URI to query all photos and
 * videos. Use Albums.CONTENT_URI to query all albums. Use Metadata.CONTENT_URI
 * to query metadata about a photo or video, based on the ID of the media. Use
 * ImageCache.THUMBNAIL_CONTENT_URI, ImageCache.PREVIEW_CONTENT_URI, or
 * ImageCache.ORIGINAL_CONTENT_URI to query the path of the thumbnail, preview,
 * or original-sized image respectfully. <br/>
 * To add or update metadata, use the update function rather than insert. All
 * values for the metadata must be in the ContentValues, even if they are also
 * in the selection. The selection and selectionArgs are not used when updating
 * metadata. If the metadata values are null, the row will be deleted.
 */
public class PhotoProvider extends ContentProvider {
    @SuppressWarnings("unused")
    private static final String TAG = PhotoProvider.class.getSimpleName();
    static final String AUTHORITY = "com.android.gallery3d.photoprovider";
    static final Uri BASE_CONTENT_URI = new Uri.Builder().scheme("content").authority(AUTHORITY)
            .build();

    /**
     * Contains columns that can be accessed via PHOTOS_CONTENT_URI.
     */
    public static interface Photos extends BaseColumns {
        /**
         * Internal database table used for basic photo information.
         */
        public static final String TABLE = "photo";
        /**
         * Content URI for basic photo and video information.
         */
        public static final Uri CONTENT_URI = Uri.withAppendedPath(BASE_CONTENT_URI, TABLE);
        /**
         * Identifier used on the server. Long value.
         */
        public static final String SERVER_ID = "server_id";
        /**
         * Column name for the width of the original image. Integer value.
         */
        public static final String WIDTH = "width";
        /**
         * Column name for the height of the original image. Integer value.
         */
        public static final String HEIGHT = "height";
        /**
         * Column name for the date that the original image was taken. Long
         * value indicating the milliseconds since epoch in the GMT time zone.
         */
        public static final String DATE_TAKEN = "date_taken";
        /**
         * Column name indicating the long value of the album id that this image
         * resides in. Will be NULL if it it has not been uploaded to the
         * server.
         */
        public static final String ALBUM_ID = "album_id";
        /**
         * The column name for the mime-type String.
         */
        public static final String MIME_TYPE = "mime_type";
    }

    /**
     * Contains columns and Uri for accessing album information.
     */
    public static interface Albums extends BaseColumns {
        /**
         * Internal database table used album information.
         */
        public static final String TABLE = "album";
        /**
         * Content URI for album information.
         */
        public static final Uri CONTENT_URI = Uri.withAppendedPath(BASE_CONTENT_URI, TABLE);
        /**
         * Parent directory or null if this is in the root.
         */
        public static final String PARENT_ID = "parent";
        /**
         * Column name for the name of the album. String value.
         */
        public static final String NAME = "name";
        /**
         * Column name for the visibility level of the album. Can be any of the
         * VISIBILITY_* values.
         */
        public static final String VISIBILITY = "visibility";
        /**
         * Column name for the server identifier for this album. NULL if the
         * server doesn't have this album yet.
         */
        public static final String SERVER_ID = "server_id";

        // Privacy values for Albums.VISIBILITY
        public static final int VISIBILITY_PRIVATE = 1;
        public static final int VISIBILITY_SHARED = 2;
        public static final int VISIBILITY_PUBLIC = 3;
    }

    /**
     * Contains columns and Uri for accessing photo and video metadata
     */
    public static interface Metadata extends BaseColumns {
        /**
         * Internal database table used metadata information.
         */
        public static final String TABLE = "metadata";
        /**
         * Content URI for photo and video metadata.
         */
        public static final Uri CONTENT_URI = Uri.withAppendedPath(BASE_CONTENT_URI, TABLE);
        /**
         * Foreign key to photo_id. Long value.
         */
        public static final String PHOTO_ID = "photo_id";
        /**
         * Metadata key. String value
         */
        public static final String KEY = "key";
        /**
         * Metadata value. Type is based on key.
         */
        public static final String VALUE = "value";
    }

    /**
     * Contains columns and Uri for maintaining the image cache.
     */
    public static interface ImageCache extends BaseColumns {
        /**
         * Internal database table used for the image cache
         */
        public static final String TABLE = "image_cache";

        /**
         * The image_type query parameter required for accessing a specific
         * image
         */
        public static final String IMAGE_TYPE_QUERY_PARAMETER = "image_type";

        // ImageCache.IMAGE_TYPE values
        public static final int IMAGE_TYPE_THUMBNAIL = 1;
        public static final int IMAGE_TYPE_PREVIEW = 2;
        public static final int IMAGE_TYPE_ORIGINAL = 3;

        /**
         * Content URI for retrieving image paths. The
         * IMAGE_TYPE_QUERY_PARAMETER must be used in queries.
         */
        public static final Uri CONTENT_URI = Uri.withAppendedPath(BASE_CONTENT_URI, TABLE);

        /**
         * Foreign key to the photos._id. Long value.
         */
        public static final String PHOTO_ID = "photos_id";
        /**
         * One of IMAGE_TYPE_* values.
         */
        public static final String IMAGE_TYPE = "image_type";
        /**
         * The String path to the image.
         */
        public static final String PATH = "path";
    };

    // SQL used within this class.
    protected static final String WHERE_ID = BaseColumns._ID + " = ?";
    protected static final String WHERE_METADATA_ID = Metadata.PHOTO_ID + " = ? AND "
            + Metadata.KEY + " = ?";

    protected static final String SELECT_ALBUM_ID = "SELECT " + Albums._ID + " FROM "
            + Albums.TABLE;
    protected static final String SELECT_PHOTO_ID = "SELECT " + Photos._ID + " FROM "
            + Photos.TABLE;
    protected static final String SELECT_PHOTO_COUNT = "SELECT COUNT(*) FROM " + Photos.TABLE;
    protected static final String DELETE_PHOTOS = "DELETE FROM " + Photos.TABLE;
    protected static final String DELETE_METADATA = "DELETE FROM " + Metadata.TABLE;
    protected static final String SELECT_METADATA_COUNT = "SELECT COUNT(*) FROM " + Metadata.TABLE;
    protected static final String WHERE = " WHERE ";
    protected static final String IN = " IN ";
    protected static final String NESTED_SELECT_START = "(";
    protected static final String NESTED_SELECT_END = ")";

    /**
     * For selecting the mime-type for an image.
     */
    private static final String[] PROJECTION_MIME_TYPE = {
        Photos.MIME_TYPE,
    };

    private SQLiteOpenHelper mOpenHelper;
    protected static final UriMatcher sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

    protected static final int MATCH_PHOTO = 1;
    protected static final int MATCH_PHOTO_ID = 2;
    protected static final int MATCH_ALBUM = 3;
    protected static final int MATCH_ALBUM_ID = 4;
    protected static final int MATCH_METADATA = 5;
    protected static final int MATCH_METADATA_ID = 6;
    protected static final int MATCH_IMAGE = 7;

    static {
        sUriMatcher.addURI(AUTHORITY, Photos.TABLE, MATCH_PHOTO);
        // match against Photos._ID
        sUriMatcher.addURI(AUTHORITY, Photos.TABLE + "/#", MATCH_PHOTO_ID);
        sUriMatcher.addURI(AUTHORITY, Albums.TABLE, MATCH_ALBUM);
        // match against Albums._ID
        sUriMatcher.addURI(AUTHORITY, Albums.TABLE + "/#", MATCH_ALBUM_ID);
        sUriMatcher.addURI(AUTHORITY, Metadata.TABLE, MATCH_METADATA);
        // match against metadata/<Metadata._ID>
        sUriMatcher.addURI(AUTHORITY, Metadata.TABLE + "/#", MATCH_METADATA_ID);
        // match against image_cache/<ImageCache.PHOTO_ID>
        sUriMatcher.addURI(AUTHORITY, ImageCache.TABLE + "/#", MATCH_IMAGE);
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int match = matchUri(uri);
        if (match == MATCH_IMAGE) {
            throw new IllegalArgumentException("Cannot delete from image cache");
        }
        selection = addIdToSelection(match, selection);
        selectionArgs = addIdToSelectionArgs(match, uri, selectionArgs);
        List<Uri> changeUris = new ArrayList<Uri>();
        int deleted = 0;
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        db.beginTransaction();
        try {
            deleted = deleteCascade(db, match, selection, selectionArgs, changeUris, uri);
            db.setTransactionSuccessful();
        } finally {
            db.endTransaction();
        }
        for (Uri changeUri : changeUris) {
            notifyChanges(changeUri);
        }
        return deleted;
    }

    @Override
    public String getType(Uri uri) {
        Cursor cursor = query(uri, PROJECTION_MIME_TYPE, null, null, null);
        String mimeType = null;
        if (cursor.moveToNext()) {
            mimeType = cursor.getString(0);
        }
        cursor.close();
        return mimeType;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        // Cannot insert into this ContentProvider
        return null;
    }

    @Override
    public boolean onCreate() {
        mOpenHelper = createDatabaseHelper();
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder) {
        return query(uri, projection, selection, selectionArgs, sortOrder, null);
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder, CancellationSignal cancellationSignal) {
        int match = matchUri(uri);
        selection = addIdToSelection(match, selection);
        selectionArgs = addIdToSelectionArgs(match, uri, selectionArgs);
        String table = getTableFromMatch(match, uri);
        SQLiteDatabase db = mOpenHelper.getReadableDatabase();
        return db.query(false, table, projection, selection, selectionArgs, null, null, sortOrder,
                null, cancellationSignal);
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        int match = matchUri(uri);
        int rowsUpdated = 0;
        SQLiteDatabase db = mOpenHelper.getWritableDatabase();
        db.beginTransaction();
        try {
            if (match == MATCH_METADATA) {
                rowsUpdated = modifyMetadata(db, values);
            } else {
                selection = addIdToSelection(match, selection);
                selectionArgs = addIdToSelectionArgs(match, uri, selectionArgs);
                String table = getTableFromMatch(match, uri);
                rowsUpdated = db.update(table, values, selection, selectionArgs);
            }
            db.setTransactionSuccessful();
        } finally {
            db.endTransaction();
        }
        notifyChanges(uri);
        return rowsUpdated;
    }

    protected static String addIdToSelection(int match, String selection) {
        String where;
        switch (match) {
            case MATCH_PHOTO_ID:
            case MATCH_ALBUM_ID:
            case MATCH_METADATA_ID:
                where = WHERE_ID;
                break;
            default:
                return selection;
        }
        return DatabaseUtils.concatenateWhere(selection, where);
    }

    protected static String[] addIdToSelectionArgs(int match, Uri uri, String[] selectionArgs) {
        String[] whereArgs;
        switch (match) {
            case MATCH_PHOTO_ID:
            case MATCH_ALBUM_ID:
            case MATCH_METADATA_ID:
                whereArgs = new String[] {
                    uri.getPathSegments().get(1),
                };
                break;
            default:
                return selectionArgs;
        }
        return DatabaseUtils.appendSelectionArgs(selectionArgs, whereArgs);
    }

    protected static String[] addMetadataKeysToSelectionArgs(String[] selectionArgs, Uri uri) {
        List<String> segments = uri.getPathSegments();
        String[] additionalArgs = {
                segments.get(1),
                segments.get(2),
        };

        return DatabaseUtils.appendSelectionArgs(selectionArgs, additionalArgs);
    }

    protected static String getTableFromMatch(int match, Uri uri) {
        String table;
        switch (match) {
            case MATCH_PHOTO:
            case MATCH_PHOTO_ID:
                table = Photos.TABLE;
                break;
            case MATCH_ALBUM:
            case MATCH_ALBUM_ID:
                table = Albums.TABLE;
                break;
            case MATCH_METADATA:
            case MATCH_METADATA_ID:
                table = Metadata.TABLE;
                break;
            default:
                throw unknownUri(uri);
        }
        return table;
    }

    protected final SQLiteOpenHelper getDatabaseHelper() {
        return mOpenHelper;
    }

    protected SQLiteOpenHelper createDatabaseHelper() {
        return new PhotoDatabase(getContext());
    }

    private int modifyMetadata(SQLiteDatabase db, ContentValues values) {
        String[] selectionArgs = {
            values.getAsString(Metadata.PHOTO_ID),
            values.getAsString(Metadata.KEY),
        };
        int rowCount;
        if (values.get(Metadata.VALUE) == null) {
            rowCount = db.delete(Metadata.TABLE, WHERE_METADATA_ID, selectionArgs);
        } else {
            rowCount = (int) DatabaseUtils.queryNumEntries(db, Metadata.TABLE, WHERE_METADATA_ID,
                    selectionArgs);
            if (rowCount > 0) {
                db.update(Metadata.TABLE, values, WHERE_METADATA_ID, selectionArgs);
            } else {
                db.insert(Metadata.TABLE, null, values);
                rowCount = 1;
            }
        }
        return rowCount;
    }

    private int matchUri(Uri uri) {
        int match = sUriMatcher.match(uri);
        if (match == UriMatcher.NO_MATCH) {
            throw unknownUri(uri);
        }
        return match;
    }

    protected void notifyChanges(Uri uri) {
        ContentResolver resolver = getContext().getContentResolver();
        resolver.notifyChange(uri, null, false);
    }

    protected static IllegalArgumentException unknownUri(Uri uri) {
        return new IllegalArgumentException("Unknown Uri format: " + uri);
    }

    protected static String nestSql(String base, String columnMatch, String nested) {
        StringBuilder sql = new StringBuilder(base);
        sql.append(WHERE);
        sql.append(columnMatch);
        sql.append(IN);
        sql.append(NESTED_SELECT_START);
        sql.append(nested);
        sql.append(NESTED_SELECT_END);
        return sql.toString();
    }

    protected static String addWhere(String base, String where) {
        if (where == null || where.isEmpty()) {
            return base;
        }
        return base + WHERE + where;
    }

    protected static int deleteCascade(SQLiteDatabase db, int match, String selection,
            String[] selectionArgs, List<Uri> changeUris, Uri uri) {
        switch (match) {
            case MATCH_PHOTO:
            case MATCH_PHOTO_ID: {
                String selectPhotoIdsSql = addWhere(SELECT_PHOTO_ID, selection);
                deleteCascadeMetadata(db, selectPhotoIdsSql, selectionArgs, changeUris);
                break;
            }
            case MATCH_ALBUM:
            case MATCH_ALBUM_ID: {
                String selectAlbumIdSql = addWhere(SELECT_ALBUM_ID, selection);
                deleteCascadePhotos(db, selectAlbumIdSql, selectionArgs, changeUris);
                break;
            }
        }
        String table = getTableFromMatch(match, uri);
        changeUris.add(uri);
        return db.delete(table, selection, selectionArgs);
    }

    protected static void execSql(SQLiteDatabase db, String sql, String[] args) {
        if (args == null) {
            db.execSQL(sql);
        } else {
            db.execSQL(sql, args);
        }
    }

    private static void deleteCascadePhotos(SQLiteDatabase db, String albumSelect,
            String[] selectArgs, List<Uri> changeUris) {
        String selectPhotoIdSql = nestSql(SELECT_PHOTO_ID, Photos.ALBUM_ID, albumSelect);
        deleteCascadeMetadata(db, selectPhotoIdSql, selectArgs, changeUris);
        String deletePhotoSql = nestSql(DELETE_PHOTOS, Photos.ALBUM_ID, albumSelect);
        SQLiteStatement statement = db.compileStatement(deletePhotoSql);
        statement.bindAllArgsAsStrings(selectArgs);
        int deleted = statement.executeUpdateDelete();
        if (deleted > 0) {
            changeUris.add(Photos.CONTENT_URI);
        }
    }

    private static void deleteCascadeMetadata(SQLiteDatabase db, String photosSelect,
            String[] selectArgs, List<Uri> changeUris) {
        String deleteMetadataSql = nestSql(DELETE_METADATA, Metadata.PHOTO_ID, photosSelect);
        SQLiteStatement statement = db.compileStatement(deleteMetadataSql);
        statement.bindAllArgsAsStrings(selectArgs);
        int deleted = statement.executeUpdateDelete();
        if (deleted > 0) {
            changeUris.add(Metadata.CONTENT_URI);
        }
    }
}